Yes, VALENCES is a Scrabble word!

Letter values in Scrabble US: V 4, A 1, L 1, E 1, N 1, C 3, E 1, S 1.

Is it a valid word?

VALENCES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

(biology) a relative capacity to unite or react or interact as with antigens or a biological substrate
(chemistry) a property of atoms or radicals; their combining power given in terms of the number of hydrogen atoms (or the equivalent)